1. Field of the Invention
This invention relates generally to improvements in propeller systems for developing a propulsive force, and more particularly, it pertains to a new outboard apparatus for propelling marine vessels, such as boats ships, etc.
2. Description of the Prior Art
Historically, various propeller and paddling apparatus have been developed for propelling different types of vehicles in water. While screw type propellers are one of the most common means for propelling boats and ships, such apparatus have a number of disadvantages. They have low efficiency because a lot of energy is lost in high speed screw propellers due to their friction with water, wake forming, vortices, cavitation, etc. The traditional outboard engines with screw propellers are plunged into the water and that creates a considerable braking force, especially when such engines are used for propelling small boats. Such engines are also relatively noisy, which may be undesirable in many situations, such as for fishing or pleasure boats, etc.
While the traditional propulsion paddling systems with reciprocating movement of the paddles, do not create any braking force, they also have low efficiency and the mechanization of such paddling systems is far too complicated to render them practical.
Many improvements of the screw propellers have been suggested throughout the years. Numerous patents and researches have been devoted to development of propeller systems wherein the propeller blades are pivoted simultaneously with rotation of the driving shaft and to the problem of optimizing such cyclic variations of the orientation of individual blades. Some of such systems utilize rotation of propeller blades or paddles not only around the axis of the driving shaft but also around complementary axes of rotation for more effective exertion of propulsive force. The basic concept presented in these systems is that the usable propulsive force is developed as a result of rotating the blades around two axes of rotation with variable orientation of the rotated blades relative to the driving shaft.
Propulsion apparatus are known (U.S. Pat. Nos. 1,284,282 to Fitzpatrick, U.S. Pat. No. 1,450,454 to Roney, U.S. Pat. No. 1,667,140 to Clark, U.S. Pat. No. 1,923,249 to Abram) wherein blades of feathering type extend radially from the driving shaft and are rotated around radial axes simultaneously with rotation of the driving shaft. In the paddling position, the blades are held in a plane parallel to the axis of the driving shaft and in the feathering position, the blades are held in a plane perpendicular to the axis of the driving shaft. A serious drawback of such systems is that, in the process of changing from one position to the other, the blades have to be rotated 90 degrees around their longitudinal axes with a considerable resistance of the fluid and low paddling and propulsion efficiency during such rotation. That is why such systems have low propulsion efficiency in comparison with screw type propellers.
There are also known propulsion apparatus wherein the propeller blades are oriented and rotated in the planes parallel to the driving shaft (U.S. Pat. No. 3,270,820 to Frazier, British patent No. 217,223 to Pensovecchio). Although having advantages in respect to the propellers with feathering blades, such apparatus with only two blades mounted in a plane perpendicular to the propeller shaft also have low efficiency and irregular power consumption. Different combinations of such propulsion apparatus are cumbersome and the mechanisms employed to effect their operations is complicated. For these reasons, a limited success has been obtained by such type of apparatus.
The present invention seeks to overcome the deficiencies of known propulsion systems and to benefit from the advantages that may be expected from the new method and apparatus.
The object of the invention is to provide a reliable propulsion apparatus for marine vessels, such as boats and ships with improved propulsion and energy efficiency.
The invention is based on my discovery that an effective propulsive force in a liquid or gaseous fluid can be developed by rotating a driving shaft with four fluid moving means, such as blades or paddles, which are simultaneously rotated with the same speed around two intercrossed axes which are perpendicular to the axis of the driving shaft and to each other. Each fluid moving means is positioned and rotated in a plane generally parallel to the axis of the rotated driving shaft. The driving shaft and the fluid moving means are interconnected so that two of the fluid moving means are parallel to the axis of the driving shaft and are oriented in opposite directions, while the other two of the fluid moving means are parallel to an axis which is perpendicular to the axis of the driving shaft and are oriented in the same direction. Each two adjacent fluid moving means are rotated in different directions (clockwise and counterclockwise) in perpendicular planes. During such double rotations, the radial extensions of the fluid moving means relative to the driving shaft are changing as a function of the angle of rotation. As a result, the circumferential velocity and the speed of paddling motion of the fluid moving means is changing during each propulsion stroke in the water, resembling a fishtail or frog-leg action of the aquatic nature. Both sides of the fluid moving means are used consecutively as paddling surfaces.
In the preferred embodiment of the propulsion apparatus, a horizontal driving shaft with a rotated planetary gear-box is mounted on the stern of a boat over the surface of the water so as not to create any braking force for the moving boat. The gear-box includes four engaged bevel miter gears mounted on four radial shafts. A couple of additional planet bevel miter gears are also mounted on these radial shafts and are engaged with a sun bevel miter gear which is disposed coaxially to the hollow driving shaft. Four paddles mounted on the ends of the radial shafts are constrained by the planetary gear engagements to rotate with the same speed around the intercrossed axes of the driving shaft and the axes of the radial shafts. During these rotations, the positions of the paddles are changed from horizontal to vertical and, as a result, the paddles extend into the water wherein the propulsion force is developed. Circumferential velocities of the blades are gradually accelerated when they move downward during each propulsion stroke.
Simultaneously with the paddling process, the rotated paddles can work as blades of a double screw propeller if they are mounted with angles of incidence in the planes of rotation around the radial axes. Because the orientations of the fluid moving means relative to the longitudinal axis of the boat are changed during the rotation of the driving shaft, their angles of incidence must be variable.
The propulsion and energy efficiency of the typical outboard engines can also be improved by mounting in them the present propulsion apparatus instead of the traditional screw propellers. Two vertical driving shafts with the gear-boxes and the fluid moving means can be mounted in the extension case of the outboard engine and rotated in opposite directions for developing a unidirectional propulsive force.